Disposable diapers often have a means for gathering up at the waist to improve a fit of the waist opening portion while worn, such as fastening tapes made of an elastic member (see Japanese Patent Publication No. 7-61351 and Japanese Utility Model Publication No. 4-10817) or an elastic member that is provided at the rear waist portion.
In order to gather at the waist by the above-mentioned conventional means, an elastic member having elasticity must be fixed at a prescribed position of a diaper with a necessary step of stretching the elastic member in a series of a production system. Therefore the elastic member cannot be transported, fixed, and assembled into a diaper in the same manner as other members, which has caused poor productivity. Further, a complicated processing step is involved which increases cost.
Japanese Patent Laid-Open No. 7-231913 discloses a porous sheet in which areas having no elasticity but moisture permeability alternate with areas having no moisture permeability but elasticity. The publication further discloses the use of the porous sheet in absorbent articles, for example, as a back sheet of a disposable diaper. However, the publication neither discloses nor suggests use of the porous sheet as a fastening tape for diapers.